[Chinese herbal medicine Fuzheng Huayu recipe inhibits liver fibrosis by mediating the transforming growth factor-β1/Smads signaling pathway].

Objective: To investigate the mechanism of Fuzheng Huayu recipe (FZHY), a compound traditional Chinese herbal medicine, against liver fibrosis related to transforming growth factor-β1 (TGF-β1)/Smads signaling transduction.
Methods: The research consisted of in vitro and in vivo experiments. In the in vivo experiment, 37 male Wistar rats were divided into 3 groups: 5 rats in normal group, 18 and 14 rats respectively in model and FZHY groups. Liver fibrosis was induced in rats of the model group and the FZHY group by intraperitoneal injection of dimethylnitrosamine with a dose of 10μg/kg body weight for 4 weeks. Rats in the FZHY group were administered with FZHY for 4 weeks after liver fibrosis was induced. After the treatment of FZHY, hydroxyproline (Hyp) content in rat liver tissue was assayed by Jamall's method and protein expressions of TGF-β1, TGF-β1 receptor I (TβR-I), Smad2, Smad3 and phosphorylated-Smad2/3 were analyzed by Western blotting. In the in vitro experiment, hepatic stellate cells (HSCs) were isolated from normal rats by in situ pronase/collagenase perfusion followed by density gradient centrifugation. On the 4th day of cell culture, HSCs were stimulated by 2.5 ng/mL TGF-β1 for 24 h, then incubated with the medium containing 10% FZHY-medicated serum or 10μmol/L SB-431542 (a potent and specific inhibitor of TGF-β1 receptor I kinase) for 24 h. And the HSCs without TGF-β1 stimulating were used as control group. Protein expressions and location of α-smooth muscle actin (α-SMA) and Smad3 in HSCs were assayed by immunofluorescent staining, and the image was analyzed by Image-Pro Plus 6.1 System.
Results: In the in vivo experiment, liver Hyp content in the FZHY group was reduced significantly compared with the model group. FZHY also down-regulated the protein expressions of TGF-β1, TβR-I and p-Smad2/3 in fibrotic liver tissue. In the in vitro experiment, FZHY-medicated serum incubated with TGF-β1-stimulated HSCs significantly down-regulated the protein expression of α-SMA. It also inhibited Smad3 nuclear translocation in TGF-β1-stimulated HSCs.
Conclusion: The mechanism of FZHY against liver fibrosis is related to the regulation of TGF-β1 signaling transduction pathway by inhibition of TGF-β1 and TβR-I expressions and Smads activation in fibrotic liver tissue and HSCs.